Mn_2O_3掺杂对MnO催化氧还原性能的影响

Effect of Mn_2O_3 Doping on Catalytic Performance for Oxygen Reduction of MnO

研究了纯相MnO以及Mn_2O_3掺杂MnO氧还原催化剂的结构和性能,用XRD、SEM、HRTEM等技术对样品进行测试。结果表明,氢气还原条件下可以得到Mn_2O_3掺杂的MnO,氨气还原得到纯相MnO。用循环伏安(CV)法、Tafal曲线法、时间-电流曲线和线性扫描伏安等方法对其催化氧还原性能进行分析。研究表明:MnO催化氧还原的峰值电压在–0.1 V到–0.5 V之间,Mn_2O_3的掺杂提高了氧还原峰值电流强度和电压;旋转圆盘电极(RDE)与旋转圆盘-环盘电极(RRDE)测试表明:Mn_2O_3掺杂MnO的催化氧还原反应主要是4电子反应,而纯相MnO催化氧还原主要是2电子反应。通过本研究表明:Mn_2O_3掺杂提高了MnO的催化氧还原性能,元素不同价态离子的共存提高了催化氧还原反应的活性。

The pure MnO and Mn2 O3 doped MnO catalysts for oxygen reduction were synthesized by reducing manganese oxide under ammonia and hydrogen atmosphere separately. X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy were used to ascertain the structures and morphologies of the two kinds of catalysts. The cyclic voltammetry, Tafel, linear scanning voltammetry and current-time chronoamperometric tests were used to analyze the catalytic performance for oxygen reduction. The results show that the MnO potential of peak current of oxygen reduction locates in the range of –0.5 to –0.1 V. The doping of Mn2 O3 enhances the peak potential of oxygen reduction. Both the rotating disc electrode（RDE） and rotating ring disc electrode（RRDE） tests confirm that the ORR happens mainly through 4-electron reaction style under the catalysis of Mn2 O3 doped MnO, while it occurs through 2-electron style with the catalysis of pure MnO. It is approved that the doping of Mn2 O3 improves the catalysis of MnO. The coexistence of ions with different valents can promote the catalytic activity.